Thank you for writing to me. We can do a computer report for you if you call the office. We need to know the surface area of the pool, if you will use a blanket on the water and if so the hours a day that you will use it. The temperature desired for the pool and your city. Do you think that you might want to cool the pool in the summer? Many pools in AZ get too hot in the summer. As a general rule if a heat pump costs $100.00 a month to use in AZ, natural gas would be $300.00 to $400.00 and propane will be $500.00 to $600.00. I hope that helps.